Animal Coordination, Control and Homeostasis Flashcards
What are hormones?
They are ‘chemical messengers’ that target organs in the body
What are hormones produced by?
Endocrine glands and they are released into the blood
What do target organs do in response to its hormone?
Release another chemical susbtance
What are the seven endocrine glands?
Pituitary Thyroid Pancreas Testis Hypothalamus Adrenal Ovary
What is the pituitary gland?
Located at the base of the brain, it releases many hormones including ACTH, FSH, LH and growth hormones.
What is the thyroid gland?
Located at the base of the neck, it secretes thyroxine
What is the pancreas?
Located high in the abdomen, its cells secrete insulin and glucagon
What are the testes?
Located in the scrotum, they secrete the sex hormone testosterone
What is the hypothalamus?
Located in the brain, it produces TRH and CRH
What is the adrenal gland?
Located in each kidney, they secrete adrenalin
What are the ovaries?
Located in the pelvis, they produce the sex hormones oestrogen and progesterone
What is a target organ?
An organ that is affected by a specific hormone
What are the similarities between nerves and hormones?
They both help you respond to changes in the environment and in your body
What are the differences between nerves and hormones?
- Hormones = long-lived effect, take longer to work
- Nerves = short-lived effect, works quickly
When do the release of sex hormones increase?
During puberty, explaining the increase in growth rate at this time
What does thyroxine do?
Controls your metabolic rate (rate of respiration/hunger levels) by causing heart cells to contract more rapidly and strongly and increases rate at which proteins and carbs are broken down into cells
What happens if your produce too much thyroxine?
High metabolism = hyperactive, constant hunger, lose weight fast
What happens if you produce too little thyroxine?
Slow metabolism = depressed, tired, gain weight easily
How is the control of thyroxine concentration in the blood an example of negative feedback?
Sn increase in thyroxine concentration directly causes changes that bring about a decrease in the amount of thyroxine released into the blood
What happens in frightening/exciting situations in association with adrenalin?
An increase in impulses from neurones reaching the adrenal glands from the spinal cord triggers the release of large amounts of adrenalin into the blood
What is glycogen?
A polymer made of glucose molecules
What can happen when glycogen is broken down?
The glucose molecules can be released into the blood providing additional glucose for respiration
What does adrenalin do to the heart?
- Heart muscle cells contract more rapidly, increasing heart rate
- Heart muscle cells contract more strongly, increasing blood pressure
What does adrenalin do to the liver?
Liver cells change glycogen to glucose and release it into the blood, increasing blood sugar concentration
What does adrenalin do the blood vessels?
- Narrow those leading to other organs = reduces blood flow to organs, increasing blood pressure
- Widen those leading to muscles = increases blood flow to muscles
What is the menstrual cycle?
A cycle of changes in a woman’s reproductive system that takes about 28 days
When does the menstrual cycle occur?
From puberty (12) to menopause (50s)
What does the menstrual cycle do?
Prepares the woman’s body for the fertilisation of an egg cell (pregnancy)
What happens during the menstrual cycle?
The lining of the uterus thickens again and ovulation occurs
What is ovulation?
When an egg cell is released from an ovary
What happens on days 1-5 of the MC?
Menstruation begins and the uterus lining breaks down and is lost with the unfertilised egg cell
What happens on day 11 of the MC?
Menstruation ends and the uterus lining starts to thicken again
What happens on days 13-15 of the MC?
Ovulation occurs (ovary releases an egg)
When is fertilisation most likely?
After ovulation (days 16+)
What happens on day 23?
The egg cell travels along the oviduct to the uterus
What is the cycle controlled by?
Sex hormones oestrogen and progesterone
Where are the sex hormones released from?
The ovaries into the blood
What happens during sex?
Sperm cells are deposited in the vagina which pass through the cervix to the uterus and into the oviduct; if a sperm cell meets an egg cell, fertilisation can occur
What is contraception?
The prevention of fertilisation, methods being physical barriers or uses of hormones
Describe the male condom,
- 98% success rate
- Placed over erect penis, preventing sperm entering vagina
Describe the diaphragm/cap
- 92-96% success rate
- Placed over the cervix (entrance to the uterus), preventing sperm in the vagina entering the uterus
Describe the hormone pill and implant under skin
- > 99% success rate
- Releases hormones to prevent ovulation and thickens mucus at the cervix, making it difficult for sperm cells to pass through
What controls the release of FSH and LH?
The concentration of oestrogen and of progesterone
When does the concentration of oestrogen increase?
As the egg follicle matures
When is progesterone released?
After ovulation when the follicle becomes a structure called the corpus luteum
What does hormonal contraception use?
A progesterone-like hormone either on its own or with progesterone
What does raising hormone concentrations in hormonal contraception prevent?
The natural fall of hormone concentrations at the end of the menstrual cycle
How can problems with couples unable to get pregnant be overcome?
Using ART (Assisted Reproductive Technology), which uses hormones and other techniques to increase the chance of pregnancy
What is clomifene therapy?
- It is useful for women who rarely or never release an egg cell during their menstrual cycles
- Clomifene is a drug that helps to increase the concentration of FSH and LH in the blood
What is in vitro fertilisation (IVF)?
- An ART technique
- Overcome blocked oviducts in the woman or if the man produces very few healthy sperm cells
What happens to healthy embryos not used in the first attempt at pregnancy in IVF?
They may be frozen and stored for use another time
How do doctors today test for diabetes?
Urine tests as simple chemical tests
When is glucose released from carbohydrates in our food?
During digestion in the gut
Where is glucose broken down during respiration?
Glucose is easily absorbed from the small intestine into the blood into digestive cells
Why is it a risk to have a high concentration of glucose in the blood?
It can damage organs
What happens when blood glucose concentration rises?
It stimulates pancreatic cells to release the hormone insulin
What does insulin do?
It causes cells in the liver and other organs to take in glucose, reducing its concentration in the blood
What happens when blood glucose concentration falls?
The insulin-releasing cells in the pancreas release less and less insulin
What happens if blood glucose concentration falls too low below a certain level?
- The pancreatic cells stop releasing insulin altogether
- Another hormone called glucagon is released from other pancreatic cells
What happens when glucose is absorbed by the liver?
It is converted to glycogen, which is stored in liver cells
What is glucagon?
It causes liver cells to convert glycogen back to glucose, which is released into the blood
What happens to the amount of glucagon as blood glucose concentration increases?
It falls (inversely proportional)
What is homeostasis?
Maintaining constant conditions inside the body
What are examples of homeostasis?
- Blood glucose concentration
- Temperature control
- Water content control
What does homeostasis prevent?
Damage to the body as internal and external conditions change
What is type 1 diabetes?
When someone’s pancreatic cells that should produce insulin do not, meaning they cannot control rising blood glucose concentration
How can type 1 diabetes be detected?
When blood glucose concentration is too high, it can be detected in the urine, therefore glucose in the urine is the first test for type 1 diabetes
What is the treatment for type 1 diabetes?
They have to inject insulin into the fat layer below the skin, where it can enter the blood, causing blood glucose concentration to fall
What response does the adrenalin hormone bring about?
The ‘fight or flight’ response
What does adrenalin do the the blood glucose concentration?
It causes the liver to convert glycogen to glucose, which is released into the blood (increases)
How is thyroxine an example of negative feedback?
A decrease in levels of thyroxine triggers a release of thyroxine to increase its concentration in the blood
Describe how hormones control the menstrual cycle
- During menstruation, all 4 hormone concentration low
- After few days, FSH released from pituitary gland
- Matures ovum in follicles
- Due to follicle maturation, oestrogen encouraged to be released from ovaries
- Oestrogen causes lining of uterus to build up
- High levels of oestrogen stimulates release of LH and separates ovum from follicle
- LH inhibits further release of oestrogen to prevent release of another egg (another baby)
- Empty follicle (corpus luteum) now left to disintegrate, releasing progesterone
- High levels of progesterone inhibit further release of FSH and LH
- Progesterone maintains thickness of uterus
- If egg ceases to be fertilised, all 4 hormone levels drop and woman begins menstruating again
Why does taking high levels of oestrogen and progesterone in contraceptive pills reduce chance of pregnancy?
- High levels of progesterone inhibit FSH production, preventing eggs from maturing
- Also inhibit the production of LH so ovulation cannot take place
What happens when low levels of thyroxine in the blood are detected by the hypothalamus?
- Stimulates production of TRH
- Stimulates production of TSH from pituitary gland
- Stimulates production of thyroxine from thyroid gland
- Thyroxine travels to and reaches target organ
What are the collecting ducts responsible for?
The re-absorption of water
What does ADH stand for?
Anti-diuretic hormone
Where is ADH released from?
The pituitary gland
What does ADH do?
Prevents you from urinating
What does a diuretic do?
Helps you go to the toilet
What does ADH change?
The permeability of collecting ducts; increases so more water can be reabsorbed into the blood
What happens when there is no ADH present?
Collecting duct not permeable to water (free to pee)
Describe the role of ADH in regulating the water content in the blood
- When blood is too concentrated ADH is released from the pituitary gland in the brain, increasing permeability of collecting ducts to reabsorb more water back into the blood
- Conserves water and the person produces a small quantity of concentrated urine
- As the concentration of ADH in the kidney drops and is no longer present, the collecting ducts are not permeable to water and you are free to pee, as your blood water concentration is at a normal level
- This is an example of a negative feedback mechanism
Describe how IVF is carried out
- Fertility drug is given out to woman to stimulate eggs to mature (FSH)
- Eggs are taken from the ovaries
- Eggs are mixed with sperm in a dish for fertilisation
- Fertilised eggs develop into embryos
- When embryos are tiny balls of cells, one or two placed in the woman’s womb to develop
What does clomifene do?
Increases concentration of FSH and LH so stimulates eggs to mature and then be released
Why is a woman given FSH and LH injections before start of IVF treatment?
- Hormones stimulate her eggs to mature while still inside her before being extracted for IVF
- She will super-ovulate and release many eggs
- She will then get these harvested
Why is IVF useful for couples who risk passing on genetic disorders?
The clinician can select the healthy embryos without the genetic disorders through genetic analysis of the cells’ chromosomes under a microscope
What causes type 2 diabetes?
The person does produce insulin but their liver and muscle cells become resistant to it
How do you control type 2 diabetes?
By eating foods that contain less sugar, exercising, and using medication if needed that lowers the glucose production by the liver
How does exercise help control type 2 diabetes?
It lowers blood glucose level through respiration
How do you calculate BMI?
Mass (KG)/ HEIGHT^2 (M)
Why can’t you take insulin tablets to treat type 1 diabetes?
Hormones are proteins and so will just be digested by the enzyme pepsin and will never reach the circulatory system
Why do proteins strengthen the immune system?
Antibodies are proteins and lymphocytes make these proteins (help to fight the body from infected/pathogens)
How do you calculate waist:hip ratio?
WAIST/HIP MEASUREMENT
What is the normal body temperature
About 37 degrees celsius
Why are fevers and hypothermia dangerous?
Because they affect how well the enzymes in our bodies work
What is thermoregulation?
The control of body temperature, which keeps the temperature of the major organs close to 37
How does the hypothalamus aid in temeprature control?
- Constantly monitors temperature
- Receives info from temperature receptors in the dermis of the skin
- Receptors inside the hypothalamus detect temperature changes in the blood and brain
How does the body react if the hypothalamus detects blood or brain temperatures starting to fall below 37?
- Shivering = muscles start to contract and relax rapidly, and some of this energy released from cell respiration from shivering warms you up (kinetic to thermal)
- Contracting of erector muscles in the dermis of the skin = causes body hairs to stand upright; humans not as much effect as animals, where hair traps air next to the skin for insulation
- Reduction of blood flow near skin = keeps warm blood deeper inside the core of body, reducing rate of energy transfer to air by heating
- Decreased heat loss by radiation
How does the body react if the hypothalamus detects blood or brain temperature starting to rise above 37?
- Sweating = sweat spreads out as a thin layer over the skin epidermis where it evaporates; as it evaporates from skin to surroundings so skin cools down
- Hypothalamus increases blood flow near to surface of skin - easier for blood to transfer energy to the air
- Increased heat loss by radiation
What is vasoconstriction?
- When we are cold, the hypothalamus sends nerve impulses to small arteries deep in skin, causing them to narrow
- Reduces blood flow in capillaries near the surface of the skin and helps to reduce energy transfer to the surroundings
What is vasodilation?
- Hypothalamus causes small arteries to widen
- Increases blood flow through skin capillaries
- Brings warm blood nearer to surface of skin and increases energy transfer to the surroundings
What are the 3 main layers of skin (in order of closest to the skin first)?
Epidermis
Dermis
Adipose tissue (fat)
Why is temperature control an endorthermic reaction?
They (animals) control their temperature from within the body, not by external means
Where is urea made?
In the liver
How is urea made?
- Protein is eaten
- Protein split into amino acids by digestion
- Amino acids are used by cells to make new proteins
- Some are left over
- Waste amino acids are changed into urea in the liver
What does the kidney do?
Make urine
What does the ureter do?
Carries urine to the bladder
What is the urethra?
A ring of muscle that relaxes to allow urine to leave the body
What does the renal vein do?
Carries cleaned/filtered blood away from the kidney
What does the renal artery do?
Carries blood, oxygen and waste to the kidney
What does the bladder do?
Stores urine
Describe the section through a kidney
- Fibrous skin = covers the kidney (outer layer)
- Cortex = where waste substances pass from the blood into the kidney tubules (inside fibrous skin)
- Medulla = where collecting ducts from the kidney tubules meet (inside cortex)
- Ureter = carries urine to the bladder (tube attached from kidney to bladder, inside medulla)
What do kidney tubules do?
Remove urea and other waste substances from the blood
How does a kidney tubule work?
- Blood waste substances are carried to tubule by arteriole
- Substances carried to bowman’s capsule
- Some useful substances pass back into the blood
- Urine pass along tubule
- Some water from urine passes back into blood
- Cleaned blood goes into renal vein
- Urine goes into collecting duct
- Collecting duct carries urine to ureter
- Ureter
- Bladder
- Urethra
What is the function of the bowman’s capsule and glomerulus?
Filter small molecules from blood into 1st convoluted tube
What is the function of the 1st convoluted tube?
Selectively reabsorbs glucose from the tubule back into the blood vessels around the nephron (by active transport); other molecules left in tubule
What is the function of the collecting duct?
Carries out osmoregulation
What happens to large molecules like proteins with the nephron?
They cannot usually filter into the nephron and so stay in the blood
What process describes how urea and glucose enter the nephron?
Filtration
Name the two parts of the nephron where water reabsorption into the blood occurs
- Loop of Henle
- Collecting ducts
What is the glomerulus?
Knot of capillaries
What are the two treatments of kidney failure?
- Dialysis
- Kidney transplant
What does a dialysis machine do?
- Carried out every 2 or 3 days
- Dialysis tubing is partially permeable
- Diffusion restores the normal concentrations of dissolved substances in the blood
- Dialysis fluid contains the same concentration of useful substances as blood so glucose and useful mineral ions are not lost
- Urea diffuses out of blood into the fluid
How does a kidney transplant?
- Healthy kidney connected to blood circulation to do work on diseased kidneys
- Antigens on new kidney cells different from antigens in patient’s body, so rejection may occur
- To prevent rejection, antigens must be as similar in type as possible (siblings) or patient treated with drugs to reduce effects of immune system, meaning patient may get more infections than normal
- Antibodies in patient’s immune system may attack transplanted kidney and reject it
